Process for the production of a transparent original

ABSTRACT

Transparent originals capable of giving superior light transmission, are prepared by applying a blushing layer containing at least one of a nitrocellulose and a linear polyester resin soluble in organic solvents, onto a transparent support, marking the blushing layer, and smoothening it out with a solvent.

United States Patent Obuchi et a]. [451 Apr. 4, 1972 [s41 PROCESS FOR THE PRODUCTION OF A [56] References Cited TRANSPARENT ORIGINAL UNITED STATES PATENTS [72] 5 2 2 fi i ij g 2,739,909 3/1956 ROSCIlthal... ..117/36.7 3a Ka A awa E 2,848,752 8/1958 Bechtold ..117/36.7 3 n g P 3,031,328 4/1962 Larsen..... .117/36.7 [22] Filed: Oct. 28, 1968 3,135,622 6/1964 Ranalh ..117/63 3,236,717 2/1966 Adhikary. ..1 l7/36.7 1 1 Appl- 777,968 3,320,089 5/1967 Bourgeois... ..l17/36.7 Related U 5 Application Data 3,350,205 10/1967 Goffe ..117/36 7 [63] Continuation-impart of Ser. No. 400,231, Sept. 29, PrimHrY'EMMWFMMaY Kati 964 abandone Attorney-Ralph E. Bucknam, Jesse D. Remgold, Robert R.

Strack and Henry A. Marzullo, Jr.

[30] Foreign Application Priority Data ABSTRACT Sept. 30, 1963 Japan ..38/51841 Transparent originals capable of g g Superior light trans mission, are prepared by applying a blushing layer containing [52] US. Cl ..117/15, [17667111174235 at least one of a nitrocellulose and a linear polyester resin soluble in organic solvents, onto a transparent support, mark- 5 5 ing the blushing layer, and smoothening it out with a solvent.

1e o are 6 Claims, 1 Drawing Figure ROUGH SURFACE RECORDING LAYER r /MADE OF FILM- FORMING MATERIAL TRANSPARENT SUPPORT LAYER I WRITTEN REcoRo WRITING MEANS RECORDING STEP CLARIFICATION AND SMOOTHENING OF RECORDING LAYER BY HEAT AND/OR SOLVENT SMQOTR SURFACE TRANSPARENT RECORDING LAYER AFT A F AT &( I N A ENT ER CL is SUPPORT LAYER PROCESS FOR THE PRODUCTION OF A TRANSPARENT ORIGINAL This application is a continuation-in-part of Ser. No. 400,231, filed Sept. 29, 1964, now abandoned.

This invention relates to a process for the production of a transparent original by drawing letters and figures on a rough surface of a material and then converting the surface into a completely smooth surface.

From old times there have been on sale and utilized in large quantities materials having a considerable light transmissive property and a rough surface, on which figures and letters can be drawn by a pencil, ball-point pen or ruling pen and printings can be doneby miscellaneous printing inks. Illustrative of such material is a tracing paper, but this is unsuited for uses requiring accuracy because of itslarge expansion and contraction due to the humidity. Recently a material composed of a polyester resin base the surface of which is specially processed has been proposed and used, the polyester resin base having a small expansion and contraction coefficient due to the humidity and temperature. Many of them have a mechanically roughened surface, but some have a surface coated with a translucent layer in which a finely divided pigment is dispersed.

These materials have no trouble practically in the accuracy and ease of drawing, but encounter a difiiculty when it is desired to use them for the following object. That is to say, when these are to be enlarged and projected optically, the greatest part of light passing through the original is scattered around and therefore not only the intensity of illumination on the projected surface, but the contrast of the projected image is lowered. By a result of measuring on a marketed mat base by use of an aperture of f-8, only 2-3 percent of the light passed reached a projected surface magnified to times.

In such case it has been proposed to apply a lacquer to the original in order to raise the intensity of illumination on the projected surface or to immerse the original in a liquid in order to decrease the degree of scattering, but such processing has no effect of course for a material coated with a pigment dispersed layer. Also in the case in which a mechanically roughened surface is used, such a disadvantage is unavoidable and even a small unevenness in the coating comes out clearly on the projected surface, because the thickness of the lacquer coating has a sharp influence upon the light scattering property. The immersion of the original in a liquid is difiicult to be carried out with a practical apparatus, in particular, in the case of supporting the original in an optical system.

We have succeeded in overcoming such disadvantages accompanying the materials of the prior art as mentioned hereinbefore by a novel process comprising applying to a transparent support consisting mainly of polyethylene terephthalate, in the presence or absence of a subbing layer thereon, a blushing layer containing at least one of a nitrocellulose and an organic solvent soluble linear polyester resin to be clarified or smoothened conpletly by the action of a solvent such as a liquid solvent, heated solvent vapor or a solvent containing a resin compatible with the blushing layer, marking the blushing layer by a writing means, and then clarifying or smoothening the blushing layer by the action of a solvent.

The recording layer (a surface on which drawing is done is hereinafter referred to as the recording layer) of our invention is made sufficiently hard so that drawing of infonnations by pencil, ball-point pen, etc. is easily carried out. When drawing is carried out by a pencil, a possible writing mistake should be erasable by an eraser without destroying the recording layer.

The recording layer (blushing layer) in the present invention mainly comprises nitrocellulose, and linear polyester resins. These film-forming materials are compatible with each other so that mixtures of these may also be employed for the recording layer. They may be mixed with a suitable quantity of pigment and plasticizer. However, the wax and pigment must be limited to be as little as possible and otherwise the final transparency aimed by our invention is interfered. To fomi a recording layer having a rough surface this can be easily carried out by choosing a suitable solvent composition for the coating mixture and a drying condition. For this purpose it is adequate to cause blushing. There are two processes for this. The one is a process using a low boiling point solvent miscible easily with water, with which the moisture in the atmosphere is condensed to a coated surface cooled by the heat of evaporation and a high molecular material dissolved is deposited as fine particles to form a rough surface. It is necessary for the process to control severely the drying conditions but it can be satisfactorily adapted for use on a large scale. The second process consists of selecting a solvent composition so that a poor solvent may be mainly retained in the final period of drying. This process is not so much influenced by the moisture in atmosphere.

The surface so obtained has a finely rugged surface and facilitates the drawing by a pencil, ball-point pen without repelling and blurring of ink.

A hazed recording layer obtained by any of these methods is recorded and then sprayed with a solvent having a high boiling point relative to the resin or with lacquer consisting of said solvent with an appropriate resin or plastic agent dissolved therein, or subjected to vapor of said solvent for being made transparent. Then, in all cases including lacquer spray, light scattering structure of recording layer is destroyed to make a continuous transparent layer. This features the present invention. This continuous transparent layer is fonned by melt of recording layer or by filling up of cavities of said layer without melting thereof.

Since the recording layer is subjected to a local high mechanical action by drawing, the layer should strongly adhere to the polyester base film. The adhesion between the recording layer and the polyester film remarkably improves by a such coating comprising solvent-soluble, linear polyester resins.

The recording layer, be it provided directly on the polyester film or not, comprising a solvent soluble, linear polyester resin, exhibits an intense affinity to the film.

Such linear polyester resin includes Vitel PE-200 or Vitel PE 207 which are marketed by Goodyear Tire & Rubber Co. or Ester Resin from Toyobo C0,, Ltd. in Japan.

When such linear polyester resin is mixed with nitrocellulose, the resulting recording layer forms a hard and opaque coating quite suitable for drawing film. Preferably the mixing ratio lies between :20 to 20:80 (linear polyester resin nitrocellulose).

As the content of nitrocellulose increases, the hardness of the layer increases.

When the recording layer solely comprises nitrocellulose, the use of subcoated polyester film is recommended.

When such a resin is dissolved in a solvent having a relatively low boiling point such as acetone, methylethyl ketone, methyl acetate, ethyl acetate and spread, a hazed surface is obtained as a result of the above-stated condensation of moisture caused by evaporation of solvent.

A true solvent having a low boiling temperature, compounded with a solvent having a high boiling point, and not dissolving the true solvent may be applied.

Even though the spraying and lacquering in this case bring a coating unevenness, the transparency is scarcely influenced thereby. This is favorably compared with the lacquering to a recording material whose support itself composes a rough surface.

Furthermore, as regards the transparency of the finished original, the conventional materials are far inferior to this and the lacquering to material in the prior art and therefore the contrast of the illumination intensity on a projected surface is superior as compared with the prior art. This makes it possible to utilize a light sensitive material having a relatively low sensitivity and a low contrast, which will be noticed by industrial users.

When a translucent original having a rough surface as in the prior art is projected to ten times by a lens having an aperture of f-8, only less than 10 percent of the light given to the original reaches the projected surface even after the lacquering. On the other hand, when the transparent original in accordance with our invention is used, more than 25 percent of the light can be brought to a l times projected surface.

The following examples are illustrative of our invention.

EXAMPLE 1 A polyester transparent base of 120 micron thickness was first coated with the following subbing auxillary solution so as to give a film of 2-3 micron thickness upon the dried base.

A linear polyester resin Methyl ethyl ketone Toluene 100 parts by weight 400 pans by weight 200 parts by weight After drying, the following solution was applied thereto in such a manner that the quantity applied amounted to 4-5 g./m. after drying. The drying air was maintained at a temperature of 35 C and a humidity of 60-65 percent RH.

Nitrocellulose 100 parts by weight Acetone 400 parts by weight Methylene chloride 200 parts by weight Methanol 50 parts by weight Butyl acetate Toluene Ethyl acetate l5 parts by weight 25 parts by weight I0 parts by weight EXAMPLE 2 A transparent polyester base coated with the same subbing solution as in the Example 1 was coated with the following solution to give a recording layer. The quantity applied was 2-2.5 g./m. on dry base.

Nitrocellulose (low viscosity) lOO parts by weight Acetate 400 parts by weight Ethyl acetate 300 parts by weight Methanol 50 parts by weight Butyl acetate 50 parts by weight Drying air was maintained at a temperature of 35 C and a humidity of 60-65 percent RH. The dried film was muddy white and drawn clearly by a pencil or ruling pen. The following solution was applied uniformly and thinly to the recorded layer by the roller coating process.

l0 parts by weight 43 parts by weight 7 parts by weight Linseed oil Toluene Butyl acetate EXAMPLE 3 The following solution was applied to a support subbed as in the Example 2.

80 parts by weight parts by weight 375 parts by weight 125 parts by weight Nitrocellulose (low viscosity) Dibutyl phthalate Acetone Methanol Drying air was maintained at a temperature of C and a humidity of 70 percent RH. The quantity applied was 33.5

g./m. on dry base. The dried film was slightly opaque and could be drawn by a pencil or ruling pen. The recording layer was rubbed by cotton soaked with the following solution:

Dibutyl phthalate Toluene As the clarification scarcely occurred under this condition, the treated film was placed in a thermostat maintained at C. for 5 minutes to give a complete transparency. Then a styrene-alkyd resin dissolved in toluene was applied uniformly and thinly thereto to reduce the adhesiveness thereof. The last process may be substituted by the washing with a petroleum type solvent.

EXAMPLE 4 A coating solution having the following composition was directly applied to a transparent polyester base of 150 micron thickness.

Linear polyester resin 50 pans by weight Methyl ethyl ketone 200 parts by weight Acetone 50 parts by weight Methylene chloride 50 parts by weight Then it was, dried by drying air maintained at a temperature of 40 C. and a humidity of 65 percent RH to give a slightly opaque film. The quantity applied was 2.5-3 g./m. on dry base. After drawing by a pencil or ruling pen was carried out, the following solution was sprayed vigorously on the film thereby to cause transparency.

Nitrocellulose Dibutyl phosphate n-Amyl acetate Butyl acetate Toluene EXAMPLE 5 A coating solution having the following composition was directly applied to a transparent polyester base of micron thickness:

Linear polyester resin 35 parts by weight Nitrocellulose l5 parts by Weight Methyl ethyl ketnne 200 parts by weight Acetone 50 parts by weight Toluene 50 parts by weight Methylene chloride 25 parts by weight Phenol-modified alkyd resin Toluene 50 parts by weight I50 parts by weight The linear polyester was not dissolved in this solution in the least and the clarification was completely accomplished.

What is claimed is:

l. A process for the production of a transparent original for optical projection of an image, which comprises applying to a transparent support consisting mainly of polyethylene terephthalate, a blushing layer consisting of a nitrocellulose and an organic solvent-soluble linear polyester resin, the ratio between said resin and said nitrocellulose being between 80:20 and 20:80, said layer being capable of being clarified by the action of a solvent, applying writing means to deposit marking material in the blushing layer and then clarifying the blushing layer by the action of a solvent.

2. A process for the production of a transparent original according to claim 1, wherein said transparent support additionally contains a subbing layer.

claimed in claim I, wherein said solvent capable of clarifying or smoothening said blushing layer is a solvent containing a resin compatible with the blushing layer.

6. A process for production of a transparent original claimed in claim 1, wherein said writing means is a pencil, a pen, or a ball-point pen. 

2. A process for the production of a transparent original according to claim 1, wherein said transparent support additionally contains a subbing layer.
 3. A process for production of a transparent original claimed in claim 1, wherein said solvent capable of clarifying or smoothening said blushing layer, is a liquid solvent.
 4. A process for production of a transparent original claimed in claim 1, wherein said solvent capable of clarifying or smoothening said blushing layer is a heated solvent vapor.
 5. A process for production of a transparent original claimed in claim 1, wherein said solvent capable of clarifying or smoothening said blushing layer is a solvent containing a resin compatible with the blushing layer.
 6. A process for production of a transparent original claimed in claim 1, wherein said writing means is a pencil, a pen, or a ball-point pen. 